Fuse-plug.



C. D. PLATT.

FUSE PLUG.

APPLICATION FILED JULY 14, 1914.

1,21 5,701 Patented Feb. 13, 1917.

WITNESSES: llVl/E/V TOR A TTOH/VEY and, as fuse plugs are sealed and there is no eLAnnndE n. PLATT, or nnmsnronr, commc'ncu'r.

FUSE-PLUG.

Specification of Letters Patent. Patentd Feb,-13, 1917,

Applicaiton filed July 14, 1914. Serial No. 850,912.

To all whom it may concern;

Be it known that I, CLARENCE D. PLA'i'r, a citizen of the United States, residing at Bridgeport, county of Fairfield, State of Connecticut, have invented an Improvement in Fuse-Plugs, of which the following is a specification.

This invention has for its object to provide an inexpensive and efiicient fuse plug that will clearly indicate a blown or dead fuse. In plugs of this character it is very necessary that the fuse should be clearly visible, as the plugs are permanently other practical means for locating a blown fuse. In use, fuse plugs are commonly mounted in blocks inclosed in wall pockets or cabinets, which are necessarily often located in dark places now constructed, it is frequently practically impossible to see through the plug windows clearly enough to detect a blown fuse, especially if the fuse is of low rating.

My present invention enables me to overcome this objection and provide a fuse-plug in which the fuse is clearly visible under all the ordinary conditions of use.

In the accompanying drawing forming a part of this specification,

Figure 1 is a perspective of a. fuse plug embodying my novel invention;

Fig. 2 a face view with the cap removed;

Fig. 3 a face view of the base with all of the parts removed except the center contact;

Fig. 1 a section on the line H in Fig. 1, looking in the direction of the arrows, and

Fig. 5 is a removed.

10' denotes the body which is ordinarily made of porcelain and is provided with a chamber 11 having an internal shoulder 12. The exterior of the body is provided with a thread to receive\the screw shell "13 and the lower end of the body is provided with the usual center contact '14. At one side of the chamber I preferably provide a groove View of the combustible disk 15 and on the opposite side of the body.

from the groove I provide an opening 16 which extends downward and to the outer side of the threaded portion of the body, the lowerend of the opening being covered by the screw shell, as clearly shown in Fig. 4,

the purpose of which will presently be explamed. It will be seen therefore that when the fuse is intact it will be clearly visible owing to the contrasting color of the nonmetallic disk, and when the fuse blows itwill either destroy or effectively discolor the disk so that the condition is readily ap parent. I

'Upon theshoulder I place a non-metallic disk 17 of any suitable material, preferably of white or light colored paper. The disk in the present instance is shown as provided with a tab which extends into opening 16 and prevents the disk from shifting, al-. though thisisnot an essential feature of construction. [19 denotes'the fuse which is connected to the centercontact in the usual manner, extends upward through the groove, then across .the face 'of'the disk and down ward through-the opening and is soldered to the screw shell as at 20. The upper end ofthe plug isjclosed by. a disk 21 of mica and a cap 22 having a central opening 23 through Whichjthe mica -is exposed and which constitutes thef'windowof the plug. The cap is shown" as retained in place by closing the edge thereof under a flange 2 1 i at the upperend of the body. Whether the.

fuse burnsout on blows from an over-. load or 'a shortcircui't, the disk, which con trasts in color with the fuse, will de-' stroyed, or if not wholly destroyed will be charred anddis'color'ed to suchan extent as to clearly indicate that'the fuse is blown. As it is necessary'that the portion of the fuse lying over the .disk shall burn or blow first I coat the portion of thefuse lying in the'groovewith a protecting covering, indicated by. 25,. as for example a mixture of plaster of Paris or whiting with water, which will, protect that portlon of the 'fuse'and increase its conductivity, thus insuring. that when the fuse blows, the portion. lying across the surface of the disk will be destroyed first and will either destroy the disk orwill char or discolor, it to such an extent as to show clearly through the window of the' lug and render it quite easy to detect a blown fuse even when the plugs are in a relatively. dark place. This for the reason that when the plug is in operative condition the white disk shows clearly through. the-.window and the destruction or charring and discoloration of 2 ne ther the disks indicates clearly that the fuse is V blown even Where the fuse itself would not be visible.

Having, thus described my invention I Y claimz' 'l, d fuse block comprising a substantially Icup-shaped insulating body providing a lon- I gitudin'ally elongated and centrally dis posed chamber therein, said chamber being provided with an internal shoulder, a window of transparent material closing the open end of said chamber, a center contact in the closed end of said chamber a screw shell inclosing a portion of said he y, atelitale diskof inflammable material resting upon said shoulder, and a fuse having one end'attached to said center contact and the other end attached to'said screw shell, an intermediate portion of said fuse being extended transversely across the outer face of said tell-tale disk. 2. A; base block comprising'a substantially cup-shaped insulating body providing a iongitudinally-elongated and centrally-disposed chamber therein, said chamber being providedwith an internal shoulder, a window ref-said chamber, -closed-end of said of transparent material closing the open end chamber, a screw shell inclo'sing a portion of said body, a telltale disk otflinflammable material restingiupon said. shoulder, and iii fuselhaving one end -'[a'ttached to saidcente'r contact and passing a'center contact in the upwardly thrbugh said chamber and transversely across the outer face of said telltale dis the portion of said fuse below the face of said disk being provided with a protective covering.

3, A fuse block body providcomprising a substan--' tially cup-shaped insulating ing a longitudinally-elongated and centrally closedend of said chamber, a. screw shell inclosing a portion of said body and covering said channel, a tell-tale disk of inflammable material resting upon said shoulder, and a fuse having one end attached to said center contact, passing upwardly Within said groove, thence transversely across the upper face of said disk and thence through said channel to connection with said shell. 7

ln testimony' whereof l affix my signature in presence of two witnesses.

.cnanuncn n. rnarr. Witnessesi i 

